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arXiv · 1301.6563

Magnetization dynamics in Co2$MnGe/Al2$O3$/Co tunnel junctions grown on different substrates

M. Belmeguenai·H. Tuzcuoglu·F. Zighem·S-M. Chérif·Y. Roussigné·P. Moch·K. Westerholt·A. El Bahoui·C. Genevois·A. Fnidiki
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Abstract

We study static and dynamic magnetic properties of Co2MnGe (13 nm)/Al2O3 (3 nm)/Co (13 nm) tunnel magnetic junctions (TMJ), deposited on various single crystalline substrates (a-plane sapphire, MgO(100), Si(111)). The results are compared to the magnetic properties of Co and of Co$_{2}$MnGe single films lying on sapphire substrates. X-rays diffraction always shows a (110) orientation of the Co$_{2}$MnGe films. Structural observations obtained by high resolution transmission electron microscopy confirmed the high quality of the TMJ grown on sapphire. Our vibrating sample magnetometry measurements reveal in-plane anisotropy only in samples grown on a sapphire substrate. Depending on the substrate, the ferromagnetic resonance spectra of the TMJs, studied by the microstrip technique, show one or two pseudo-uniform modes. In the case of MgO and of Si substrates only one mode is observed: it is described by magnetic parameters (g-factor, effective magnetization, in-plane magnetic anisotropy) derived in the frame of a simple expression of the magnetic energy density; these parameters are practically identical to those obtained for the Co single film. With a sapphire substrate two modes are present: one of them does not appreciably differ from the observed mode in the Co single film while the other one is similar to the mode appearing in the Co$_{2}$MnGe single film: their magnetic parameters can thus be determined independently, using a classical model for the energy density in the absence of interlayer exchange coupling.

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M. Belmeguenai, H. Tuzcuoglu, F. Zighem, S-M. Chérif, Y. Roussigné, P. Moch, K. Westerholt, A. El Bahoui, C. Genevois, A. Fnidiki. 2013-01-28. Magnetization dynamics in Co2$MnGe/Al2$O3$/Co tunnel junctions grown on different substrates. https://doi.org/10.1166/sl.2013.3064

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